Air and light distributor unit



0, 1963 L. A. ARCHER 3,101,038

AIR AND LIGHT DISTRIBUTOR UNIT Filed Aug. 3, 1959 4 Sheets-Sheet 1 LU/lI g l k\\\\\\\\\\\\\ INVENTOR ATTORNEYS 0, 1963 L. A. ARCHER 3,101,038

AIR AND LIGHT DISTRIBUTOR UNIT Filed Aug. 3, 1959 4 Sheets-Sheet 2 n. 1Y I 1 a k \RM 1: i {a TM -v s I X I 13 1.- Q 1 A? l w a 1 1: s 1 11 1 11 [51 1x 5 l\ 1*. 1 U 1 5 K 1 a 1 m H INVENTOR [5'] Q U ZeeddrafierATTORNEYS 1963 L. A. ARCHER AIR AND LIGHT DISTRIBUTOR UNIT 4Sheets-Sheet 3 Filed Aug. 5, 1959 INVENTOR Lee 4. flrafier ATTORNEYSAug. 20, 1963 L. A. ARCHER 3,101,038

AIR AND LIGHT DISTRIBUTOR UNIT I Filed Aug. 3, 1959 4 Sheets-Sheet 4 4 4INVENTOR Lee a drain ORNEYJ United States Patent 3,101,038 AIR AND LIGHTDESTRBUTOR UNIT Lee A. Archer, Wheaten, llll., assignor to The Pyle-National Company, Chicago, 111., a corporation of New Jerse y Filed Aug.3, 1959, Ser. No. 831,282

8 Claims. (Cl. 984fl) This invention relates to improvements inventilating and illuminating apparatus and more particularly relates tosuch an apparatus particularly adapted to air condition and illuminaterooms and the like.

A principal object of the invention is to provide an improved form ofair and light distributor unit of the class described so constructed asto provide a comfortable condition of air diffusion in the livingportion of the room with no down drafts.

Another object of the invention is to provide an improved air and lightdistributor unit recessed within a false ceiling of the room, togetherwith an improved form of air diffusing and bathing means directing theair straight down into the room and so constructed as to avoid thejoining together of the air streams where two devices may be mountedend-to-end in the ceiling of the room.

A still further object of the invention is to provide a combined air andlight distributor unit of a type adapted to be recessed within a falseceiling substantially flush with the false ceiling, in which the air isintroduced from -a plenum chamber of the unit outside of the source oflight for the unit, and in which the plenum chamber is so arranged as toconvert part of the velocity head of the air entering the chamber intostatic head and to redirect the endwise velocity components of the airin an ineificient manner, effecting the direction of air turbulentlyfrom the unit straight down into the room.

A still further object of the invention is to provide a light andventilating unit adapted to be recessed within a false ceiling and besubstantially flush with the ceiling having a trofler light housinghaving elongated fluorescent tubes therein with a ventilating ductleading into the trofler light housing above the fluorescent tubes intoa plenum-chamber, so arranged as to partially change the velocity headof the air into static head and to direct the air from the plenumchamber in uniform quantities per unit length with uniform velocity headwithout horizontal velocity components, to dissipate this verticalvelocity head by turbulence and direct the air from the plenum chamberin spaced relation with respect to the fluorescent tubes in a straightdown direction at a low velocity head.

These and other objects of the invention will appear from time to timeas the following specification proceeds and with reference to theaccompanying drawings wherein:

FIGURE 1 is a fragmentary perspective View of an air and lightdistributor unit constructed in accordance with the invention, showing aseries of air and light distributor units recessed within a falseceiling, with a main air distributor duct supplying the units, and withpart of the false ceiling broken away and shown in section;

FIGURE 2 is a diagrammatic transverse sectional view illustrating thepassage of air through the air and light distributor unit;

FIGURE 3 is a longitudinal sectional view taken through the air andlight distributor unit;

FIGURE 4 is an enlarged transverse sectional view taken substantiallyalong line IV-IV of FIGURE 3, and illustrates wherein the lightdifl'usion means may include either a glass lens or a louvered panel;

FIGURE 5 is a bottom plan view of a cover section for the plenum chamberfor the unit, showing the deflector vanes extending along opposite endsthereof;

FIGURE 6 is a bottom plan view of the air damper valve and housing,showing the deflector vane and baflle 3,101,038 Patented Aug. 2t), 1963arrangement extending along opposite sides of the damper valve andpreventing the high static and velocity heads in this region fromcausing a disproportionate quantity or velocity of flow from this areaof the plenum.

FIGURE 7 is a fragmentary perspective view of one of the light traps forcarrying a glass lens, and accommodating the air to pass straight downalong the outer sides of the lens, looking at the light trap from theinside thereof.

In the embodiment of the invention illustrated in the dnawings, I haveshown in FIGURE 1 a ceiling 10 having an air supply duct 11 extendingtherealong and depending therefrom. I have also shown a false ceiling 12spaced beneath the ceiling 1i and shown as extending along the bottom ofthe air duct 11 and having a plurality of air and light distributorunits 13 recessed therein substantially flush with said false ceilingand supplied with air through flexible conduits 14 leading from saidsupply duct and suitably connected with the air and light distributorunits 13.

The false ceiling 12 is diagrammatically shown in FIG- URE 2 as havingopenings 15 therein for receiving the air and light distributor units 13and accommodating the mounting of the units substantially flush with thefalse ceiling.

As shown in FIGURES 3 and 4, each air and light distributor unit 13comprises a troffer light housing 16 having side walls 17 extendingupwardly and inwardly from opposite sides thereof and end walls 19connecting said side walls together. The side and end walls 17 and 19are flanged at the lower ends thereof as indicated by referencecharacter 2% to engage the undersurface of the false ceiling 12 aroundthe opening 15 and are constructed to accommodate a lens 21 or alouvered bottom plate 22 to be mounted substantially flush with theceiling (FIG- URE 4).

The side walls 17 of the troffer light housing extend upwardly and curveinwardly from shouldered portions 23 of said housing and terminate intovertical wall portions 24, turned inwardly at their upper end portions,and forming a top cover for the troiter light housing, having a centralopening 25 therein intermediate the ends thereof, through which extendsa generally cylindrical collar or damper valve housing 27. The collar 27has a butterfly type of damper valve 29 suitably mounted therein andincluding a pair of damper blades so pivoted on a common pivot pin 31.The damper blades 30' are biased toward an open position into engagementwith a stop 32 on the upperend of an adjustment screw 33, by a torsionspring 35 encircling the hinge pin 31. The adjustment screw 33 isthreaded within a cross member 37 extending across the collar 27 andsuitably secured to the wall thereof at its opposite ends. Theadjustment screw 33 is slotted at its lower end to receive a screwdriver or the like to turn said adjustment screw and raise or lower thestop 32 with respect to the pivot pin 31 to vary the open positions ofthe damper blades 30 with respect to the valve housing 27 and the flowof air into a plenum chamber 40 extending for a substantial portion thelength of the trofler light housing. I

The lower margins of the plenum chamber 40 are defined by a flatdeflector plate or balfle 41 terminating along its sides in spacedrelation with respect to the side walls thereof, adjacent the upper endsof the inwardly turned wall portions 17, to provide air passageways 43for the passage of air along the inner sides of said wall portions andsuitably coated to form reflectors 44 for the trofter light housing.

A reflector plate 45 reflecting light emanating from laterally spacedelongated fluorescent tubes 47, supported beneath said reflector plate,is suitably secured to and extends along the bottom of the flat baflle4-1 and beyond p of the plenum chamber.

oneness the ends thereof. The reflector plate 45 has downwardly inclinedbafiies 49 extending from the length thereof and generally parallel tolines drawn tangent to the surfaces of the fluorescent tubes 47, andspaced radially therefrom. The bafiles 4% terminate into bafi'les 5d ofan inverted V-shape in cross section, the end portions of which aregenerally parallel to the baffles 4-9 and serve to aid in deflecting theair along the wall portions 44 to prevent the air from contacting thefluorescent tubes 4'7.

The fluorescent tubes 47 are carried at their opposite ends in the usualmounting brackets 51 located at opposite ends of the trolier lighthousing 16. The mounting brackets 51 may carry the usual sockets andconductors (not shown) connected with the usual electric circuitry toeffect energization of the fluorescent tubes 47, in a manner well knownto those sltilled in the art and forms no part of the present inventionand is not herein shown or described further.

Referring now in particular to the plenum chamber th, and thecooperation of the collar or valve chamber 27 with the flat deflectorplate ll, for partially changing the verse center thereof and in directalignment with the valve chamber 27 are tabs or baflles 53 (FIGURES 3, 4and 6). The tabs or baflles 53 extend in front of and along op positelyinclined deflector vanes 54 inclined in opposite directions from thetransverse center line toward the ends of the plenum chamber. The tabs53 each have a generally vertically extending front face 55 and sidewfll" d5 diverging outwardly in the planes of the oppositely inclinedcenter deflector vanes 54- and have cars 57 at the upper inner cornersthereof. The cars 57 of the tabs 53 are adapted to be welded orotherwise secured to side walls 53 depending from a top cover portion 59for the plenum chamber 48* (FIGURES 3, 4 and 6).

The tabs or bafiles 53 extend over the greater part of the inner edgesof vanes 54 and serve to deflect the velocity head and restrict thestatic head of the air bouncing from the baflle plate ll along thep-lenumchamber 4d, and to thereby prevent a disproportionate quantity orvelocity of flow from the region of the passageways 43.

The vanes 54, as shown in FIGURE 3, have tabs 61 extending from theouter sides thereof, adapted to be welded or otherwise secured to theside Walls 58 of the cover portion 59 for the plenum chamber 4d. Asshown in the bottom plan view in FIGURE 4, four vanes 54 are mounted oneach side of the cover portion 5% of the for receiving and supportingthe lens 21.

plenum chamber 4i two being located on each side of the transversecenter of the plenum chamber. The vanes on oneside of the transversecenter of the plenum chamber are inclined outwardly with respect to thetransverse center of the deflector plate 41 toward one end of the plenumchamber. The vanes 54 on the opposite side of the transverse center ofthe plenum chamber and deflector plate 41 are inclined outwardly withrespect to the transverse center of the plenum chamber toward theopposite end Spaced outwardly of the vanes 54 are vanes-63 extendingparallel to the vanes dd and extending along the plenum chamber abovethe discharge passageways 43 for substantially the length thereof. The

first vanes 63 are shown as being mounted on the cover portion 59 andare like the vanes 5'4 except that they extend closer to the center ofthe plenum chamber than the vanes 54. The remaining vanes 63 are mountedon side walls 62 of cover portions 64 for the plenum chamber 4d. Thevanes 54- and oS form in eifect inemcient turbine blades along which theair flows and goes out. The outthe lower surface of the flanges 2d goingair leaving the spaces between the vanes 54 and 63 impinges against theoutgoing air which was deflected by vanes 54 and 63 resulting in acombined turbulent air stream emerging through the discharge passageways43 in a straight down direction without endwise velocity components.This combined air stream flows along the reflectors M outside of thefluorescent tubes 4'7 at a low velocity with an optimum cooling effecton the fluorescent tubes.

Referring now to FIGURES 3, 4 and 7, and the mounting of the lens 21along the bottom of the troifer light housing, accommodating thedownward direction of the air and shielding the light of the fluorescenttubes 47, light traps es extend along each side of the trofler lighthousing is beneath the shouldered portion 23 thereof.

Each light trap 65 has a glass channel 66 opening toward thelongitudinal center of the trolf'er light housing Each light trap 65also hasa horizontal wall portion 67 spaced upraardly from the channel65 by a plurality of spaced spac rs 63, forming a central air slot 79 inthe space therebetween (HGURE 7) and longitudinally spaced air slots 71on opposite sides of said central air slot. The slots 71 have vanes '73therein and extending beneath the horizontal wall portions 67andinclined in opposite directions from the central air slot7d to catchthe air flowing through the air slots '71 and to reverse the endwisevelocity components, resulting from impingement of the air ilow alongreflectors 4:3 with the lens 21, so that when the airemerging from slots75 impinges against the air from slots 71 the longitudinal velocitycomponents are canceled in the same manner as they were at the dischargepassageways 43.

7t; leading vertically therethrough along the inner legs of upwardly anddownwardly facing angle members 7'7 and 79 respectively. As shown inFIGURE 4, the upwardly facing angle member 77 defines the outer marginsof the vertical air slots 75, and the horizontal leg of the angle member'77 extends horizontally over the air slots 75' to shield said air slotsfrom light and to dene t the air into said air slots. The horizontallegs or the angle members 7% extend outwardly toward a stepped wallportion 8 of the trofler light housing 16 to further shield the framefrom light, and have spaced hinges Ell suitably secured to the uppersides thereof, and forming a means for securing the light traps and theglass 21 to the troffer light housing; As herein shown, the hinges 81each have a vertically extending leg 33 having a hooked uper end portion84 adapted to extend through an apertured portion 85 in the shoulder 23and also has an opposite leg 86, abutting the outside of a vertical leg87 0f the angled member 79. The glass lens and the light trapssupporting said glass lenses, therefore, may be readily secured to thetroffer light housing 16 in depending relation with respect to theshouldered portions 23 thereof With the lower surfaces thereofsubstantially flush with of said trotfer light frame.

The light trap 65 in addition to forming a support lmeans'for the glasslens 21 and shielding the air discharge passageways-along opposite endsof the glass lens from glaringlight, also cooperates with the inclinedvanes fldand -63 to reduce the endwise components of air and to directthe air straight downwardly of the trolfer light housing at a lowvelocity, and to thereby avoid drafts that would occur by theaccumulation of air at opposite ends of the trolfer light frame,particularly where a series of trotfer light frames are supported inendwise relation with respect to each other, as diagrammatically shownin FIGURE 1. I

In the modification of the invention shown hand half of FTGURE 4, t

louvered grill 22 has been substituted for the glass lens El. In thisform of the in the right I invention, a plate 89 extends along thebottom edges of the trofler light frame inwardly and outwardly of themargins thereof and forms a slidable support for the louvered grill Z2accommodating sliding of the grill into position along the inwardlyextending portion of the plate 87-9 and under retaining strips 90,extending inwardly of spacer strips 91 extending along inner wallportions 93 of the troifer light housing. The space between the plate 89and the retainer plate 90 forms a channel to slidably receive a reduced:end portion 95 of the louvered grill 22, to retain said louvered grillin position and accommodate insertion and removal of the louvered grillfrom the trotfer light housing 16, in an obvious manner.

In this form of the invention the air passes directly downwardly throughthe louvers of the louvered grill at a low velocity with no drafts.

it may be seen from the foregoing that the trolfer light housing of theinvention provides a simplified form of air and light distributor unit,in which the air is maintained away from the region of the fluorescenttubes, and thereby avoids the impairment of the efllciency of the tubescaused by undue cooling of the tubes.

it may still further be seen that the flat deflector 41, the baffles ortabs 55, and the oppositely facing vanes 54 and 63 inclined in oppositedirections from the transverse center of the troifer light housing allcontribute to convert part of the velocity head of the air entering thevalve chamber 27 to static head and that this static head serves todeflect the air with its velocity head into the vanes which cause theremaining velocity heads to oppose each other in such a manner thattheir power is dissipated in turbulence and also to eliminate theendwise velocity components of the air in a straight down directionalong the inner walls 44 of the troiier light housing, for directionthrough the light traps 65 or the louvered grill 22 straight downwardlyat a low velocity with no drafts.

It should further be understood that for the air control attained by thepresent invention to be done by conventional means, either a plenumchamber would be required which would have to be of sufficient size toconvert all of the entering velocity head into a static head, anduniform flow and direction would then be achieved by the use of a highfriction drop static pressure baffle, resulting in a plenum chamber ofsuch size as to be impractical; or an additional supply of staticpressure from the duct system would be required which would have to beof sufficient magnitude to allow the air flow to be redirected andproportioned due to its friction drop through foraminous material. Withthe second method, the total pressure drop would be considerably higherand the sound generated by throttling this pressure would beobjectionable in normal installations.

It should further be understood that the light and distributor unit ofthe invention avoids the accumulation of relatively large volumes of airat the ends of the unit which would be a cause of drafts where two unitsare connected together in endwise relation with respect to each other,and that by directing the air straight downwardly, in addition toeliminating drafts also avoids dirt smudges on the ceiling or theadjacent walls, which has heretofore been objectionable with ceilingventilating units, as Well as providing amore uniform distribution ofthe air without detracting from the efficiency of lighting.

While I have herein shown and described one form in which my inventionmay be embodied, it should be understood that various variations andmodifications of the invention may be attained without departing fromthe spirit and scope of the novel concepts of the invention as de finedby the claims appended hereto.

I claim as my invention:

1. In combination with a ceiling of a space to be illuminated andventilated, a false ceiling spaced below said ceiling, an air and lightdistributor unit in said false coiling comprising a troifer lighthousing having upwardly and inwardly extending inner side wall portionsforming a light trough above the level of said false ceiling, areflector extending along said housing along the upper margins of saidinner wall portions and having edge portions spaced inwardly from saidinner wall portions to form downwardly opening air passageways,elongated fluorescent tubes extending along said housing beneath saidreflector, a plenum chamber above said reflector, an air inlet leadinginto said plenum chamber from the top thereof at substantially thetransverse center of said plenum chamber, a plurality of verticallyextending vanes extending across said air passageways, the vanes onopposite sides of the transverse center of said plenum chamber beinginclined in opposite directions towards the opposite ends of said plenumchamber and reducing the endwise velocity components of the air anddirecting the air for discharge downwardly through said air passagewaysin a generally straight downwardly direction, and parallel batflesextending vertically along the inner sides of the central vanes of saidoppositely inclined vanes and deflecting the stream of air entering saidplenum chamber and restricting the stream of air bouncing from thebottom of said plenum chamber, to prevent the conversion of the statichead of air into a velocity head.

2. In combination with a ceiling of a space to be illuminated andventilated, a false ceiling spaced below said ceiling, an air and lightdistributor unit in said false ceiling comprising a troffer lighthousing having upwardly extending inner wall portions forming a lighttrough above the level of said false ceiling, a reflector extendingalong said housing adjacent the upper margins of said wall portions andhaving edge portions spaced inwardly from said wall portions to formdownwardly opening air passageways, elongated fluorescent tubesextending along said housing beneath said reflector, a plenum chamberextending along said housing above said reflector, an inlet into saidplenum chamber from the top thereof adjacent the transverse centerthereof, a flat battle extending along the top of said reflector andfacing said air inlet, vertically extending vanes spaced along oppositesides of said plenum chamber and extending across said air passageways,said vanes on opposite sides of the transverse center of said plenumchamber being inclined in opposite directions and effecting theimpingement of the air coming into the spaces between said vanes withthe air going out from the spaces between said vanes, and therebyreducing the endwise velocity components of the air and effecting thedischarge of the air downwardly through said air passageways enenallystraight downward directions, and downwardly and outwardly inclinedbaflle-s eX- tending along opposite edges of said reflector in outwardlyspaced relation with respect to said fluorescent tubes for deflectingthe downwardly passing air from said fluorescent tubes.

3. An air and light distributor unit adapted for mounting in a falseceiling comprising a trotfer light housing having upwardly extendinginner wall portions forming a light trough above the level of the falseceiling, a reflector extending along said housing along the uppermargins of said wall portions and having edge portions spaced inwardlyfrom said wall portions to form downwardly opening air passagewaysextending for substantially the length of said housing, elongatedfluorescent tubes mounted in said housing beneath said reflector, aplenum chamber above said reflector and extend-ing along said housingfor substantially the length thereof, an air duct leading into saidplenum chamber from the top thereof intermediate the ends thereof, meansconverting part of the stream of air entering said plenum chamber into astatic pressure head and reducing the endwise velocity components of airalong said plenum chamber comprising a flat baffle plate facing said airinlet, vertically disposed deflector vanes extending across said airpassageways, said vanes on opposite sides of the transverse center ofsaid plenum chamber being inclined in the direction of flow of airtowards the ends of said plenum chamber and effecting the impingement ofthe air coming into the spaces between said vanes with the outgoing airleaving the spaces between said vanes, to thereby reduce the endwisevelocity components of air passing through said outlet passageways anddirect the air through said outlet passageways in generally straightdownward directions, and baffle means extending vertically along theinner sides of the central deflecting vanes at opposite sides of saidflat bafiie and deflecting the stream of air entering said plenumchamber and restricting the static head of air bouncing from said flatbaflie, to thereby prevent the conversion of the static head of air intoa velocity head and assure the discharge of air downwardly along saidside walls in a generally straight down direction.

' 4. In a ceiling no draft air and light distributor unit, a

troirer light housing having upwardly and inwardly extending wallportions forming a light trough and having vertical Wall portionsforming an upward continuation of said inwardly extending wall portionsand forming a plenum chamber, a reflector extending along the uppermargins of said upwardly and inwardly extending inner wall portions,elongated fluorescent tubes in said light trough beneath said reflector,an air inlet into said plenum chamber from the top thereof andintermediate the ends thereof, opposite sides of said reflector beingspaced in- Wardly of said inner wall portions, the spaces betweenopposite sides of said reflector and said inner wall portions formingair passageways leading from said plenum chamber along said inner wallportions, spaced substantial distances outwardly of said fluorescenttubes, and means for reducing the endwise components of air in saidplenum chamber and discharging the air through said passageways in astraight down direction comprising a plurality of vertically extendinginclined vanes extending across said air passageways and inclinedoppositely from the transverse center of said plenum chamber in anupward direction toward the ends of said plenum chamber, a flat baifleextending along said reflector in alignment with the inlet, andpositioned to cause the air entering said plenum chamber through theinlet to bounce and to thereby convert part of the air stream into astatic head of air, and baffles extending vertically along the center ofthe vanes and deflecting the air stream and restricting the stream ofair bouncing off of said flat baflies to pre- 53. vent adisproportionate quantity and velocity of flow of air from the region\of said passageways.

5. In an air-light trofler, an elongated trotler housing forming alighting trough for fluorescent lighting tubes, means forming acorrespondingly elongated plenum chamber at the upper portion of thetroffer, an inlet for said plenum chamber comprising a relatively smallopening intermediate the ends of said plenum chamber and receiving aircfrom a source at increased pressure and directing the air into theplenum chamber in the form of a stream having longitudinal endwisevelocity components and downward transverse components, said plenumchamber having an elongated outlet formed on each side thereof extendingfor a substantial length of said troiier housing and disposed to providean air passageway along the side of the lighting trough andcommunicating with the lower portion of the troffer, and inclineddeflector vanes inclined in opposite directions on opposite longitudinalsides of said inlet toward the respective ends of the trotfer housingand being disposed in alignment with each said elongated outlet tointercept portions of the stream of air to reduce endwise velocitycomponents and promoting uniform diffusion of air through said outlets.

6. In an air-light troifer as defined in claim 5, said deflector vaneshaving tabs extending from the outer sides thereof for securing saidvanes to an adjoining Wall of said plenum chamber.

7. In an air-light troffer as defined in claim 5, said inlet having acollar comprising an adjustable valve, whereby the flow of supply orreturn air throughthe troffer may be adjustably controlled. a

8. In an air-light t-roiter as defined in claim 5, a flat baffle platein said plenum chamber directly beneath said inlet for engagement byincoming air, thereby to convert part of the velocity head to staticpressure.

References Cited in the file of this patent UNITED STATES PATENTS Kurthet al Nov. 15, 1960

1. IN COMBINATION WITH A CEILING OF A SPACE TO BE ILLUMINATED ANDVENTILATED, A FALSE CEILING SPACED BELOW SAID CEILING, AN AIR AND LIGHTDISTRIBUTOR UNIT IN SAID FALSE CEILING COMPRISING A TROFFER LIGHTHOUSING HAVING UPWARDLY AND INWARDLY EXTENDING INNER SIDE WALL PORTIONSFORMING A LIGHT TROUGH ABOVE THE LEVEL OF SAID FALSE CEILING, AREFLECTOR EXTENDING ALONG SAID HOUSING ALONG THE UPPER MARGINS OF SAIDINNER WALL PORTIONS AND HAVING EDGE PORTIONS SPACED INWARDLY FROM SAIDINNER WALL PORTIONS TO FORM DOWNWARDLY OPENING AIR PASSAGEWAYS,ELONGATED FLUORESCENT TUBES EXTENDING ALONG SAID HOUSING BENEATH SAIDREFLECTOR, A PLENUM CHAMBER ABOVE SAID REFLECTOR, AN AIR INLET LEADINGINTO SAID PLENUM CHAMBER FROM THE TOP THEREOF AT SUBSTANTIALLY THETRANSVERSE CENTER OF SAID PLENUM CHAMBER, A PLURALITY OF VERTICALLYEXTENDING VANES EXTENDING ACROSS SAID AIR PASSAGEWAYS, THE VANES ONOPPOSITE SIDES OF THE TRANSVERSE CENTER OF SAID PLENUM CHAMBER BEINGINCLINED IN OPPOSITE DIRECTIONS TOWARDS THE OPPOSITE ENDS OF SAID PLENUMCHAMBER AND REDUCING THE ENDWISE VELOCITY COMPONENTS OF THE AIR ANDDIRECTING THE AIR FOR DISCHARGE DOWNWARDLY THROUGH SAID AIR PASSAGEWAYSIN A GENERALLY STRAIGHT DOWNWARDLY DIRECTION, AND PARALLEL BAFFLESEXTENDING VERTICALLY ALONG THE INNER SIDES OF THE CENTRAL VANES OF SAIDOPPOSITELY INCLINED VANES AND DEFLECTING THE STREAM OF AIR ENTERING SAIDPLENUM CHAMBER AND RESTRICTING THE STREAM OF AIR BOUNCING FROM THEBOTTOM OF SAID PLENUM CHAMBER, TO PREVENT THE CONVERSION OF THE STATICHEAD OF AIR INTO A VELOCITY HEAD.